[PATCH v2] overlay/029: fix test failure with nfs_export feature enabled

[PATCH v2] overlay/029: fix test failure with nfs_export feature enabled

[Amir Goldstein]

When overlayfs nfs_export feature is enabled by default in either kernel
config or module parameters, this test fails:

    mount: /tmp/8751/mnt: mount(2) system call failed: Stale file handle.
    cat: /tmp/8751/mnt/bar: No such file or directory

The reason is that nfs_export depends on index feature and with index
feature enabled, an upper/work dirs cannot be reused for mounting with
a different lower layer.

To reproduce the failure do:
  echo Y > /sys/module/overlay/parameters/index
  echo Y > /sys/module/overlay/parameters/nfs_export
before running the test.

Fix the failure by explicitly re-creating upper/work dirs.

Reported-by: Chengguang Xu <cgxu519@mykernel.net>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
 tests/overlay/029 | 6 ++++++
 1 file changed, 6 insertions(+)

V2:
- Update commit message s/index/nfs_export feature
- Document how to test failure

diff --git a/tests/overlay/029 b/tests/overlay/029
index 1d2d2092..17f58de7 100755
--- a/tests/overlay/029
+++ b/tests/overlay/029
@@ -68,12 +68,18 @@ _overlay_mount_dirs $SCRATCH_MNT/up $tmp/{upper,work} \
 cat $tmp/mnt/foo
 $UMOUNT_PROG $tmp/mnt
 
+# re-create upper/work to avoid ovl_verify_origin() mount failure
+# when index is enabled
+rm -rf $tmp/{upper,work}
+mkdir -p $tmp/{upper,work}
 # mount overlay again using lower dir from SCRATCH_MNT dir
 _overlay_mount_dirs $SCRATCH_MNT/low $tmp/{upper,work} \
   overlay $tmp/mnt
 cat $tmp/mnt/bar
 $UMOUNT_PROG $tmp/mnt
 
+rm -rf $tmp/{upper,work}
+mkdir -p $tmp/{upper,work}
 # mount overlay again using SCRATCH_MNT dir
 _overlay_mount_dirs $SCRATCH_MNT/ $tmp/{upper,work} \
   overlay $tmp/mnt
-- 
2.17.1